The present invention relates to industrial circuit breakers and particularly to apparatus for controlling closing solenoid initiated closure thereof.
The subject closure control apparatus has particular, but not necessarily limited application to stored energy reclosure type circuit breakers, such as that disclosed in commonly assigned, copending application, Ser. No. 52,276, filed June 25, 1979, now Pat. No. 4,251,702. The disclosure of this copending application is specifically incorporated herein by reference. As therein disclosed, a circuit breaker is equipped with a separate charging mechanism which is charged and then discharged to charge a spring-powered operating mechanism capable, when charged, to propel breaker movable contacts from a tripped open position to a closed position and, when discharged or tripped, from their closed position to their tripped open position. The charging mechanism also has the capability of being sustained in its charged condition while the operating mechanism is charged so as to be prepared to abruptly recharge the operating mechanism immediately after it has been discharged. Thus, the circuit breaker can be closed, tripped open, and immediately reclosed. To control closure of the circuit breaker, a hook is incorporated to releaseably hold the movable contacts in an intermediate hooked open position against the closing force of a charged operating mechanism. To accommodate breaker closure from a remote location, a closing solenoid is utilized to articulate the hook pursuant to releasing the movable contacts from their hooked open position. Should the breaker close in on a fault and immediately trip open, and if a charge is stored in the charging mechanism, the operating mechanism is immediately recharged. If the closing solenoid is again electrically energized due to inadvertently sustained closure of a remote close switch, the hook is held removed and, with recharging of the operating mechanism, the movable contacts will close back in on the fault. This is a hazardous situation which must be avoided.
In accordance with the present invention, there is provided improved electrical closure control apparatus for reclosure type industrial circuit breakers.
A further object is to provide electrical closure control apparatus capable of preventing unintended closure of a breaker back in on a fault from which it has just been tripped open.
An additional object is to provide electrical closure control apparatus of the above character which readily accommodates externally imposed interlocking to prevent electrical closure of the circuit breaker.
Another object is to provide electrical closure control apparatus of the above character which is efficient in construction and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.